Servo unit and motor



2, 1950 w. L. HANSEN ET AL 2,505,961

SERVO UNIT AND MOTOR Filed June 27, 1946 4 Sheets-Sheet l FIG I INVENTOR WILLIAM L. HANSEN BY IRA N. HURST ATTORN EYS y 2, 1950 w. L. HANSEN ET AL 2,505,961

' SERVO UNIT AND MOTOR Filed June 27, 1946 4 Sheets-Sheet 2 Q FIG.2.

FIG. 3. 75 I3 73 74 9| mo 33 I I e2 73 m 5 I03 86 I 6 6 |o| g 84 I04 j INVENTOR 56 WILLIAM L. HANSEN BY IRA N. HU ST & ATTORN EYS y 2, 1950 w. HANSEN ET AL 2,505,961

SERVO UNIT AND MOTOR Filed June 27, 1946 4 Sheets-Sheet 3 INVENTOR WILLIAM L. HANSEN BY lRA N. HURST ATTORN EIY M y 1950 w. HANSEN ET AL 2,505,961

SERVO UNIT AND MOTOR Filed June 27, 1946 4 SheetsSheet 4 II! lll l INVENTOR WILLIAM L. HANSEN y IRA N. HURST ATTORN EYS Patented May 2, 1950 v UNITED STATES PATENT OFFIC William L. Hansen and Ira N. Hurst, Princeton,

Ind., assignors to Hansen Manufacturing Company, Inc., Princeton Indiana Ind., a corporation Application June 27, 1946, Serial No. 679,833 Claims. (Cl. 244-77) The present invention relates to accessories for airplanes and more particularly to a servo unit for remotely controlling the elevating and steering surfaces of an airplane.

In many types of planes, direct mechanical connections are made between the operating stick and the various control surfaces of the plane, in cluding the ailerons and rudder, and the force produced on these connections by the relative movement of air at the control surfaces is sometimes sufliciently great to cause physical strain on the operator or pilot. For this reason, among others, various types of servo units have heretofore been employed, many of which operate on the hydraulic pressure principle. The ways in which the various operating surfaces are interconnected are often quite complicated, tending to fall into disrepair and requiring considerable experience for efiicient operation. Moreover, it is sometimes diflicult for the pilot to bring the rudder instantly back to a straight flying course position after a steep bank, so that the operation of the plane becomes sluggish from the maneuverability standpoint.

The primary object of the invention is to provide a compact, relatively inexpensive, but highly dependable unit for controlling the operation of an airplane.

Another object is to provide an improved unit, operable by remote control, for actuating the control surfaces of an airplane.

Still another object is to provide an improved form of actuator in which the rudder is readily brought back to center for a straight flying course after the plane has executed a bank.

A further object is to provide an improved form of actuator for quickly setting a plane on the direct flying course by straight rudder regardless of the direction and extent to which a bank had been executed.

Other objects and features will be apparent as the specification is perused in connection with the accompanying drawings in which:

Figure 1 shows in perspective, and partly diagrammatic, an airplan provided with the improved form of actuator and its remote control panel.

Figure 2 is a top plan view looking into the interior of the actuator casing, the latter being broken away and showing the operating motors, cams, electromagnets and switches.

Figure 3 is an elevational view of the interior parts of the actuator and with the cover of the actuator broken away and sectioned to expose such parts.

Figure 4 is a detail view of one of the double pole or reversing switches.

Figur 5 is a detail view showing the electromagnet for operating one of the switches as shown in Figure 4. This figure also illustrates the means by which the switch is mounted directly on the relay or electromagnet unit.

Figure 6 is an isometric fragmentary view somewhat distorted for clearness and showing the gear trains and the relation between the various switches, cams and operating relays of the improved actuator.

Figure 7 is a schematic view of the circuit employed in the improved actuator.

Referring more particularly to Figure 1, reference character I designates the fuselage of an airplane, the airfoils of which are indicated at 2. The body of the plane terminates in a tail 3 to which a rudder 4 is swivelly connected in the usual manner. The body of the plane may include a cockpit 5 for a pilot, although as will be explained hereinafter the improved actuato is well suited for radio control, in which case no pilot would be necessary. In the latter event, an antenna mast 6 may be provided and an antenna 7 stretched between the mast and a suitable position on the tail. A leading conductor 8 is taken from the antenna to a box or casing 9 containing a highly sensitive receiving circuit of any suitable and well known type. The radio set contains relays (not shown) operable by the radio signals within the assigned wave length band. These relays are for the purpose of opening and closing circuits leading to the improved actuator [0 through the cable H. The general arrangement is such that when the proper signals are received the relays within the box 9 will charge or discharge one or more of the various conductors passing through th cable I I and leading into the actuator casing II). It is apparent that, if desired, a pilot sitting in the cockpit 5 may also operate the relaysby manually turning one of the dials l2. The actuator I0 is provided at each side with levers l3, I4 which are adapted to swing about th pivots l5. A connecting rod 16 extends between the upper end of the lever l3 and the upper end of an arm I! which is attached to a rod l8 spanning the body of the plane. The rod I8 is connected through suitable linkage at l9 at each end for swingably moving the ailerons 20 in a difierentlal manner when the arm I! is rotated. A connecting rod 2| extends rearwardly from the lever l3 to a lever 22 on which the rudder 4 is swingably mounted. Thus, when the rod 2| is moved to the right or left, the rudder 4 is swung in a vertical plane.

It is apparent from the foregoing that as the lever I3 is swung to the left or right about its vertical axis, the ailerons 28 are moved in different directions to cause the plane to make a right or left bank and the rudder 4 is also moved in the proper direction to complete the banking operation.

constituting part of the tail assembly there is a relatively horizontal airfoil member 23 to which elevating members 24 are swingably secured. These members are operated by a pair of arms 25 which are interconnected through a rod 23 and the latter is swivelly joined to the arm i4 through an operating rod 21. Thus, as the arm or lever 14 is swung right or left the elevating foils 24 are moved upwardly or downwardly.

The levers l3, 14 are operated by separate motors within a casing and when actuated, control the banking and elevating mechanism of the plane. The motors are under the separate and individual control of relays contained within the box 9 which may be operated through radio signals or by the pilot as by turning one or both of the dials l2. Accordingly, complete control of all the flying conditions of the airplane is obtained by operating one or both of the levers I4, 13 and the plane can be made to rise from the ground or to descend, or may be caused to make a right or left bank, and controlled by current transmitted through the cable II from the control box 9 which may be radio or manually operated.

The present invention is concerned more especially with the general design and details of the actuator II], more particularly from the standpoint of providing an improved form of mechanism, both electrically and mechanically operated, by which the connecting rods I6, 2| and 26 are caused unfailingly to be moved in the right direction and in the proper amounts to give complete and accurate control of the airplane in operation.

Figures 2 to 6 show the details of the improved actuator. The actuator or servo unit is contained preferably in a pair of deep drawn housings 28, 29 having peripherally extending flanges 30 about their edges and joined together by a number of screws 3|, with a central plate 32 interposed between the housings at the joint. This plate extends transversely across the double housing unit and serves as a support for practically all of the contained mechanism. There is a pair of electric motors 33, 34 secured to the plate 32, the lower of the two motors as shown in Figure 2 serving to actuate the lever l3 (Figure 1) through a train of gears as will be described presently and the motor 34 serves to operate the arm 14 through another set of gears. As shown in Figures 3 and 6, each set of gears which engage the pinions 35, 36 respectively of the motors 33, 34 are journalled at one end in the division plate 32 and at the other end in a support plate 35a. The latter may be secured to the plate 32 through spacing collars 36a and screws 31. There is a sub-plate 3B spaced from the main plate by collars 39 and a terminating plate 48 positioned away from the sub-plate 38 by spacers 4! and screws 42. The pinion 36 causes a segmental gear 43 (Figure 6) to swing through a limited are by means of a gear and pinion train. This train starts with a pinion 36 which meshes with a gear 44 carrying a pinion 45. The latter engages gear 46 on which pinion 41 is mounted. The latter engages gear 48 which carries pinion 49 and the latter engages gear 60 which is mounted on shaft 5| and carries at the other end gear 52 which engages segmental gear 43. There is a shaft 53 mounted at one end in the sub-plate 38 and at the other end in the terminal plate 48, this shaft extending through an oil and dust proof bearing 54 in the housing 29 to receive the lever [4. The latter may be adjustably located on the shaft by means of iongitudinally extending flutes 55 and the shaft is provided with threads 56 for receiving a lockin nut 51. The fluted portion of the shaft is pref erably tapered so that as the nut 51 is tightened. the lever I4 is caused to be rigidly secured to the fluted end of the shaft in the position. The shaft 53 also carries a. cam 58 preferably of fiber and provided with a cutaway portion 59. There is a double prong switch 68 hearing against the peripheral surface of the cam 58 (Figure 7) and on the other side of the cam there is a similar form of switch 6! also bearing against the cam. The two sets of switches 60, 6| may be conveniently secured to the sub-base 38 and the latter is cut away as indicated at 62 in Figure 2 to provide clearance for the cam 58. It will be apparent from Figure 6 that as the pinion 36 is rotated, the rotary motion is transmitted through the gears to cause the segmental gear 43 to swing in one direction or the other and to open and close either one of the switch sets 60, 6|. The lever I4 will also be caused to swing to the right or left depending on the direction in which the pinion 36 is rotated.

As stated hereinbefore, there is a second gear train positioned between the support plate 35 and the main plate 32. This gear train connects the pinion 35 of the motor 33 to the segmental gear 63 which serves to swing the arm l3 back and forth. This last mentioned gear train is constituted of a gear 64 which carries a pinion 65, the latter meshing with gear 96 which carries a pinion 61. The last mentioned pinion engages gear 68 which carries a pinion 69 and the latter engages gear 18. The gear 19 is connected through shaft H to the gear 12 which engages the segmental gear 63. The last-mentioned gear is mounted on a shaft 13 which is journalled at one end in the plate 32 and at the other end is carried by a triangular support plate 14 (Figure 2-). The outer end of the shaft 13 terminates in a tapered fluted portion similar to the shaft 53 for receiving the arm 38. The latter is secured in position by means of a nut 15 which is received by a threaded portion at the end of the shaft. Washers l6 and 51 may be interposed between the nut and lever at the outer ends of each of the shafts l3 and 53.

There is mounted on the shaft 13 a pair of earns 11, 18 having cutaway portions 19, 80, respectively. There are two double pronged switches 8|, 82 bearing against the cam 18. A similar set of double pronged switches 83, 84 bear against the cam Tl. There is also supported from the upper 01 motor side of the supporting plate 32, as seen in Figure 6, a pair of electromagnets 85, 86 which are carried on a plate 81 (Figure 6), spaced from the main plate 32 by the members 88. There is an angular shaped armature 89, swingingly mounted at 9|, associated with the electromagnet and responsive to the magnetic effects of the core 92. This armature extends downwardly for the length of the electromagnet and is terminated by a curved portion 93 which is in physical engagement with a pair of elongated leaf springs 94, 95. The spring 94 is contained between a pair of leaf springs 98, 91 insulatingly supported from the angular member 89. The leaf spring 95 is contained between a pair of leaf springs 98, 99, also supported from the armature 89. The elements of each pair of springs 98, 98 and 91, 99, also 94, 95, may be arranged edgewise to one another and insulatingly supported on a common mount as indicated in Figure 4.

The adjacent electromagnet 86, as seen in Figures 2 and 6, has associated with it an armature I which has a downwardly extending curved portion in physical contact with a pair of extended leaf springs IOI, I02 (Figure 7). Spring IOI is positioned between a pair of leaf springs I03, I04 insulatingly supported from the armature I00 in any suitable manner. The leaf spring I02 is positioned between a pair of leaf springs I05, I06 which are also insulatingly supported from the armature I00. As an impulse is applied to the coil 85, the intermediate leaf springs 94, 95 are caused to break contact with the springs 96, 98 respectively (Figure '7) and make contact with springs 91, 99 respectively. Similarly, as the electromagnet 88 is energized the springs IOI, I02 break contact with the springs I03, I respectively and make contact with the springs I04, I06.

Circuit diagram (Fig. 7)

The energizing current for the motors 33, 34 is obtained from a direct current, low voltage battery I01. The positive terminal of that battery is connected to the upper pole of,the switch 60 through a conductor I08. A wire I09 is taken from the conductor I08 and the lower pole of switch BI is connected to the wire through conductor H0. A conductor III extends from the upper pole of the switch 83 to the conductor I09 and a conductor H2 connects between the lower pole of the switch 04 and the conductor I09. The negative side of the battery I0! is connected through a switch H3 to conductor H4, also through a switch H5 to conductor H6, through a switch I II to a conductor I I8, through a switch II9 to a conductor I and finally through a switch I2I to a conductor I22. The conductor II4 connects with the leaf spring 98 and the conductor H8 connects with the leaf spring 99. The conductor H8 connects with the leaf spring I05 and conductor I20 connects with the leaf spring I04 while the conductor I22 connects with the lower pole of the switch 82. A conductor I23 is taken from the conductor I20 to the upper pole of the switch 82. A conductor I24 connects between the lower pole of the switch 50 and leaf spring 97. A conductor I25 is taken between the motor 34 and the intermediate spring 95, while a conductor I26 is connected to the intermediate spring 94. The electromagnet 85 is electrically connected to the conductor H8 and conductor I09 through the conductors I21, I28 respectively. A conductor I29 is connected between the conductor I22 and the upper pole of the switch 81. A conductor I30 is connected between the upper pole of the switch SI and the leaf spring 98. The lower pole of the switch 8] is connected through a conductor I 3i to the conductor H8. The electromagnet 86 is connected to the conductor I20 through a conductor I32 and is connected to the conductor I09 through the connection I33. A wire I34 is taken from the motor 33 to the intermediate leaf spring IOI and a wire I35 from the other side of the motor is taken to the other intermediate leaf spring I02. The upper pole of the switch 84 is connected through conductor I38 to the spring I03 and a conductor I3I is joined between the lower pole of the switch 83 and the leaf spring I08.

Assume that the cams 58, I8 and 11 have the relative positions on the shafts 53 and I3 respectively as shown and the various switches 50, 8|, 8|, 82, 83, 84 and the double pole or reversing switches 94, 95, I02, IOI are in the positions shown in the drawing. Let it be further assumed that it is desired to cant the elevators 24 (Fig. 1) upwardly at the rear edge so as to cause the plane to lift, switch H3 would be closed. A circuit can then be traced from the negative side of the battery I01 through switch I I3, spring 96 to spring 94, conductor I28 through the motor 34, conductor I25, spring 95 to spring 98, conductor I30, switch 6|, conductor H0 back to the positive side of the battery through conductors I09, I08. The motor 34 would rotate and in rotating would] turn the cam 58 clockwise. The circuit through the motor will be completed as long as the spring tip of the switch 6| rests on the outer portion of the cam 58. The motor 34 will rotate the pinion 36 causing the arm I4 to swing through an are which causes the elevators 24 (Figure 1) to raise. The motor will continue to run as long as the switch H3 is closed, but only so long as the spring tip on the switch 8| rests on the outer portion of the cam 58. Thus, the position of the jog I38 on the cam 58 determines the maximum distance over which the arm I4 will swing while the switch H3 will determine any shorter swinging distance.

In order to reverse the motor 34 so as to depress the elevators 24 as when it is desired for the plane to lose altitude, the switch H3 is opened and switch I I5 is closed. A circuit is then established from the negative side of the battery I01 .through switch H5, conductor H8 to electromagnet 85-, conductor I28 and conductors I09 and I08 back tothe positive side of the battery. When the electromagnet 85 is energized, the springs 94, move to the right and close contacts with the springs 97 and 99 respectively. The circuit is completed by going through the spring 99 to spring 95, up through conductor I25 to motor 34 (which is in the opposite direction to the circuit traced hereinbefore), through conductor I26, spring 94, spring 91 through conductor I24, switch 60 back to the positive side of the battery I01. The maximum angular travel that the arm or lever I4 can make in this opposite direction will be determined by the position of the log I39 on the cam 50 as it will be recalled that the cam at this time is turning counterclockwise. It is apparent that any intermediate angular distance can be obtained by simply opening the switch H5.

In case it is desired to bank the plane as when the ailerons 20 are to be moved in opposite directions and the rudder is to be turned to accommodate the direction of bank, the switch II! is closed. A circuit is now established from the negative side of the battery I01 to switch II'I, spring I05, spring I02, conductor I35, to the motor 33, conductor I34, spring IOI, spring I03, conductor I36, switch 84, conductor H2 and conductors I09 and I08 back to the positive side of the battery. Assume that the motor 33 rotates in the counterclockwise direction under these conditions, in which case the maximum angulartravel which the lever can make will be determined by the position of the job I40. By opening the switch. Ill after any shorter time of duration, any desired ing the switch I2I.

aeoaoai intermediate angular travel of the arm or lever I3 may be obtained.

The motor 33 can be reversed in operation to cause the lever I3 to swing in the opposite direction by opening the switch H1 and closing the switch H9. In this case, a circuit through the electromagnet 86 can be traced from the negative side of the battery through switch H9, conductor I20, conductor I32, electromagnet 86, conductor I33 and conductors I09 and I08 back to the positive side of the battery. The electromagnet 86 upon being energized causes the springs IOI, I02 to make contact with the springs I04 and I06 respectively. A circuit is then established for the motor 33 in the opposite direction by passing from the negative side of the battery through switch H9, conductor I20 to spring I04, spring IOI, through the motor 33, spring I02, spring I06, switch 83 and conductors I09 and I08 back to the positive side of the battery. Thus, by closing either switch H1 or H9, the motor 33 can be operated in one direction or the other causing the arm or lever I3 to move in either desired direction and thus, to con trol the elevation or depression of the ailerons 20 and the corresponding movement of the rudder 4.

It is desirable to be able to return the rudder and ailerons to a central position to provide for straight line flight and this can be done b clos- Inasmuch as the cam 18 will have been moved either in a clockwise or counterclockwise direction from that shown in the drawings when switch H1 or H9 had been previously operated, one or the other of the switches 8|, 82 will now be closed. Assume that the cam 18 has been moved clockwise as when switch H9 had previously been closed, switch 8| is now closed so that a circuit can be traced from the battery through switch I2 I, switch =8I, spring I05 to spring I02, through the motor 33, then conductor I34, spring IOI to I03, switch 84 (assuming that the tip end of the spring still made contact with the outer surface of cam 11) and thence back to the battery I01 through conductors I09 and I08. On the other hand, if it were desired to bring the rudder back to center after the switch I I1 had been previously closed so that cam 10 would have moved counterclockwise and caused the closure of switch 82, the following circuit can be traced; starting with the battery I01, then through switch I2I, switch 82, electromagnet 86 back to the battery through conductors I09 and I08. This will reverse the lower two switches and a circuit can now be traced for the motor from the negative side of the battery through switch I2 I, switch 82, spring I04 to spring IOI through the motor to conductor I35, spring I02 to spring I06, conductor I31 through switch 83 (assuming that this switch is on the outer surface of the cam 11) back to the battery through conductors I09 and I08. Thus, regardless of whether switch II! or H9 had closed and then opened, the closure of switch I2I will always serve to bring back the rudder to center and cause the plane to fly directly ahead.

The switches H3, H5, H1, H9 and I2I maybe contained in the box 9 (Figure 1) and these switches can conveniently be controlled b electromagnets (not shown) which are responsive to radio signals received from the antenna I or such switches may be controlled by the dials I2 and operated from a position in the cockpit 5.

From the foregoing, it is evident that we have disclosed an improved form of servo motor, all parts of which, except the circuit closing switches,

are contained within a single casing which can be conveniently mounted in the fuselage of the plane. The levers I3, I I ar positioned on opposite sides of the servo unit and the motors for operating thcsc levers and the control circuit are all contained within the unit. The parts of the servo unit including the gears, motors, switches and electromagncts, are supported from the central plate 32 so that these parts can be readily assembled and adjusted as a unit before placing the unit into its casing. The only parts that are exposed are the shaft extensions and the arms I3, I4 which are connected to the operating rods I6, 2I, and 21. Many of the parts, including the gears, switches, electromagnets and motors are duplicates of one another so that the unit as a whol can be inexpensively made and compactly arranged. Since size and weight are of predominant importance in the case of airplanes, careful consideration was necessary to provide the most compact arrangement and smallness of parts, indeed, the dimensions of the casing which houses the elevator and the aileron control device, also the rudder centering mechanism may have dimensions of only 5" long x 3 wide x 3% deep.

It will be understood that we desire to comprehend within our invention such modifications as come within the scope of the claims and the invention.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In a servo unit adapted for controlling the flight of an aircraft; a pair of electric motors, means drivingly connecting one of said motors with the bank and turn control surfaces of a craft and the other of said motors with the elevator surfaces of the craft, a, pair of control circuits for each of said motors and each closable to energize the associated motor in a different direction of movement, limit switch means operable in each direction of movement of each of said motors to make the then active control circuit ineffective thereby to hold each of said motors at predetermined limits of movement thereof, a. pair of auxiliary control circuits for said one motor for driving it in opposite directions, means responsive to movement of said one motor in either direction from its center position for making the one of said auxiliary control circuits effective which will return the said one motor to its center position, and a single switch means selectively Operable for controlling said auxiliary circuits.

2. In a servo unit adapted for controlling the flight of an aircraft; a pair of reversible electric motors, means drivingly connecting one of said motors with the bank and turn control surfaces of the craft and the other of said motors with the elevator surfaces of the craft, first and second control circuits for each of said motors closable for operating the associated motor in opposite directions of movement, normally closed limit switch means in each of said control circuits, cam means connected for being driven by said'rnotor and operable for opening said switches at predetermined limits of movement of said motors, first and second auxiliary control circuits for said one motor, normally open switch means in said auxiliary circuits, cam mean driven by said one motor and operable upon movement of said one motor from a center position for closing the one of said last mentioned switches which will make the auxiliary circuit effective that will return the said motor to its center position, and a single con- 9 trol switch for controlling both of said auxiliary circuits.

3. In a servo unit adapted for controlling the flight of an aircraft; a pair of motors, means for drivingly connecting one of said motors with the bank and turn control surfaces of the craft and the other of said motors with the elevator surfaces of the craft, means for energizing either of said motors for operation in either direction, means for limiting the amount of movement of said motors in both directions, a separate control means for said one of said motors including means connected to said last named motor and responsive to the operation of said last named motor in either direction, and also including means selectively operable to return said one motor to a center position for adjusting the surfaces connected thereto to straight line conditions regardless of the position of the said one motor at the time of actuation of said selectively operable means.

4. In a servo unit adapted for controlling the flight of an aircraft; a pair of motors, means for drivingly connecting one of said motors with the bank and turn control surfaces of the craft and the other of said motors with the elevator surfaces of the craft, means for energizing either of said motors for operation in either direction, means for limiting the amount of movement of said motors in both directions, a separate control means for one of said motors including means connected to said last named motor and responsive to the operation of said last named motor in either direction, and also including means selectively operable to return said one motor to a center position for adjusting the surfaces connected thereto to straight line conditions regardless of the position of the said one motor at the time of actuation of said selectively operable means.

5. In a servo unit adapted for controlling the flight of an aircraft; a pair of motor means, means for drivingly connecting one of said motor means with the bank and turn control surfaces of the craft and the other of said motor means with the elevator surfaces of the craft, means for energizing either of said motor means for operation in either direction, means for limiting the amount of movement of said pair of motor means in both directions, a separate control means for one of said motor means including means connected to said last named motor means and responsive to the operation of said last name-d motor means in either direction, and also including means selectively operable to return said last named motor means to a center position for adjusting thesurfaces connected thereto to straight line conditions regardless of the position of the last named motor means at the time of actuation of said selectively operable means.

WILLIAM L. HANSEN. IRA N. HURST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,334,615 Kittredge Mar. 23, 1920 1,904,801 Plutino Apr. 13, 1923 2,109,475 Fanning Mar. 1, 1938 2,397,475 Dinga Apr. 2, 1046 2,423,336 Moseley Jan. 1., 1947 

